Optical Communication Apparatus, Optical Route Switching Apparatus and Network

1. An optical communication apparatus configured to convert a client signal supplied from a client communication apparatus into an optical signal suitable for transferring over an optical network, and to convert a received optical signal into a client signal, comprising: circuitry configured to: distribute the client signal that is supplied to a plurality of signals over an optical frequency domain, based on identifiers of destinations added to the client signal, and a communication capacity of each of the destinations, wherein the client signal includes a plurality of multiplexed signals addressed respectively to the plurality of destinations, each of the plurality of multiplexed signals is provided with a respective one of the identifiers which is different for each one of the destinations; convert the distributed signals to a plurality of optical signals having different assigned center optical frequencies according to the destinations and the communication capacity of each of the destinations, each of the plurality of optical signals being output to a different output fiber that is associated with the assigned center optical frequency; wavelength division multiplex the plurality of optical signals and to output the plurality of optical signals; demultiplex a plurality of wavelength division multiplexed optical signals that are wavelength division multiplexed for each of a plurality of wavelengths; convert the demultiplexed optical signals into electrical signals; and multiplex the electrical signals, and to output the multiplexed electrical signals as a client signal without conversion or after converting the multiplexed electrical signal to an optical signal.

2. The optical communication apparatus as claimed in claim 1 , wherein the circuitry is configured to select a modulation format such that an occupied spectrum width of a requisite minimum spectrum width is obtained according to a distance and a communication capacity by which the optical signal should be transmitted.

3. An optical route switching apparatus including a function for multiplexing, demultiplexing, adding, dropping, and switching a wavelength division multiplexed signal, wherein an add/drop port includes an input/output port to the optical communication apparatus as claimed in claim 1 , and an optical frequency bandwidth for multiplexing, demultiplexing, adding, dropping, and switching is variable according to an optical spectrum width of the optical signal.

4. A system which includes an optical wavelength division multiplexing network in which a plurality of optical route switching apparatuses are connected by a plurality of optical fibers, and a plurality of client communication apparatuses, wherein the client communication apparatuses are connected via an optical communication apparatus provided in an add/drop port of the optical route switch apparatus, and wherein arbitrary client communication apparatuses communicate with each other by a wavelength path, wherein an input/output port of the client communication apparatus includes circuitry configured to provide a client signal with information for identifying a destination, and at least one of the optical route switching apparatuses is the apparatus as claimed in claim 3 , and an input/output port of an arbitrary client communication apparatus is connected to the input/output port of a plurality of arbitrary client communication apparatuses via the optical communication apparatus connected to the add/drop port of the at least one of the optical route switching apparatuses.

5. A method, implemented by an optical communication apparatus configured to convert a client signal supplied from a client communication apparatus into an optical signal suitable for transferring over an optical network, and to convert a received optical signal into a client signal, the method comprising: distributing the client signal that is supplied to a plurality of signals over an optical frequency domain, based on identifiers of destinations added to the client signal, and a communication capacity of each of the destinations, wherein the client signal includes a plurality of multiplexed signals addressed respectively to the plurality of destinations, each of the plurality of multiplexed signals is provided with a respective one of the identifiers which is different for each one of the destinations; converting the distributed signals to a plurality of optical signals having different assigned center optical frequencies according to the destinations and the communication capacity of each of the destinations, each of the plurality of optical signals being output to a different output fiber that is associated with the assigned center optical frequency; wavelength division multiplexing the plurality of optical signals and outputting the plurality of optical signals; demultiplexing a plurality of wavelength division multiplexed optical signals that are wavelength division multiplexed for each of a plurality of wavelengths; converting the demultiplexed optical signals into electrical signals; and multiplexing the electrical signals, and outputting the multiplexed electrical signals as a client signal without conversion or after converting the multiplexed electrical signal to an optical signal.

6. The method as claimed in claim 5 , further comprising selecting a modulation format such that an occupied spectrum width of a requisite minimum spectrum width is obtained according to a distance and a communication capacity by which the optical signal should be transmitted.